1. Field on the Invention
The present invention generally relates to ultrasonic surgical instruments and, more particularly, to harmonic scalpels for cutting bone and for cutting and/or coagulating tissue, for example.
2. Description of the Related Art
Ultrasonic surgical instruments can be used for the safe and effective treatment of many medical conditions. Generally, ultrasonic surgical instruments can be used to cut and/or coagulate organic tissue, for example, using energy in the form of ultrasonic vibrations, i.e., mechanical vibrations transmitted to a surgical end-effector at ultrasonic frequencies. These ultrasonic vibrations, when transmitted to organic tissue at suitable energy levels and using a suitable end-effector, may be used to cut and/or coagulate the tissue. Such instruments may be used for open procedures or minimally invasive procedures, such as endoscopic or laparoscopic procedures, for example, wherein the end-effector is passed through a trocar to reach a surgical site.
Although ultrasonic surgical instruments can perform their intended function remarkably well, the energy and vibrations created by these instruments is significant and, if not properly controlled, can unintentionally cause damage to tissue and/or bone surrounding the surgical site. As a result, several safety features have been developed to prevent, or at least reduce the possibility of, such damage from occurring. For example, some surgical instruments have been developed which include sheaths that extend around at least a portion of the end-effector. In use, these sheaths can prevent portions of the end-effector from unintentionally contacting tissue or bone surrounding the surgical site. However, these sheaths can block the surgeon's view of the surgical site, for example. As a result, the surgeon may not be able to readily ascertain the depth of their incisions and make corrective adjustments. What is needed is an improvement over the foregoing.